To maintain the homeostasis, a living body has the autonomic nervous system, the endocrine system and the immune system. Among these systems, the autonomic nervous system is relatively free from the cerebral control and acts automatically without being consciously controlled, which is the origin of the name. It mainly controls visceral functions. The autonomic nervous system comprises the sympathetic nervous system and the parasympathetic nervous system and is controlled based on a balance between these two systems. When the body is in action, the sympathetic nervous activity become predominant and the whole body is in a state of tension. On the contrary, when the parasympathetic nervous activity become predominant, the tension is loosened and the body is relaxed (Non-Patent Document 1). Sympathetic hyperactivity causes pupil dilation, tachycardia, a rise in blood pressure, substance metabolism, hyperglycemia and so on. Parasympathetic hyperactivity causes activation of the digestion and absorption system, secretion of sweat and saliva and so on. It is also known that the autonomic nervous activity relate to control of the white adipose tissue and the brown adipose tissue functions. Namely, the white fat tissue function is controlled by the sympathetic nerve and hormones in the blood, while the brown fat tissue function is controlled mainly by the sympathetic nerve (Non-Patent Document 2).
Disturbance of the balance in autonomic nervous activity leads to health troubles such as indefinite complaint (Non-Patent Document 2). As countermeasures against health troubles focusing on the autonomic nervous activity, there have been disclosed, for example, relaxing via the enhancement of parasympathetic nervous activity with the use of a rutaceous or eucalyptus essential oil (Patent Document 1), an aroma therapy for enhancing parasympathetic nervous activity by using 4-methoxystyrene (Patent Document 2), promotion of lacrimation by enhancing on the parasympathetic nervous activity with the use of a peptide (Patent Document 3) and a sympathomimetic inhibitor using an n−3 higher unsaturated fatty acid which is efficacious against autonomic imbalance such as erythrophobia and anxiety neurosis (Patent Document 4).
On the other hand, concerning phenyl lactic acid, which is known as occurring in two kinds of optical isomers, the antibacterial and antifungal effects have been merely known hitherto. That is, phenyl lactic acid is known as being produced by microorganisms belonging to the genus Lactobacillus, showing an antifungal activity on Aspergillus niger, etc., showing an increase in the concentration thereof in a culture supernatant by addition of phenylalanine during the culture (Non-Patent Document 3). Further, it is known that phenyl lactic acid produced by use of a lactic acid bacterium exerts an antibacterial effect on pathogenic Escherichia coli O-157 and methicillin-resistant Staphylococcus aureus (Patent Document 5) and so on.    Patent Document 1: JP-A-2005-272445    Patent Document 2: JP-A-2004-131436    Patent Document 3: JP-A-H11-209294    Patent Document 4: JP-A-2004-067537    Patent Document 5: JP-A-2000-300284    Non-Patent Document 1: Toshio Hagihara, et al., Iwanami Koza, Gendai Igaku no Kiso, vol. 4, Seitai no Chousetsu Shisutemu, 1999    Non-Patent Document 2: Tomifusa Kuboki, Igaku no Ayumi, vol. 181, No. 12, 1013-1015, 1997    Non-Patent Document 3: FEMS microbiology Letters 233:289-295, 2004